Which type of roughage is characterized by jointed stems and seed-like fruit?

Timothy hay is characterized by jointed stems and produces seed-like fruits, which makes it distinct from other types of roughage in the options provided. This grass is typically harvested at various stages of growth, leading to different nutritional values depending on when it's cut. The jointed stems found in Timothy hay contribute to its structure and make it fibrous, providing important roughage for equine diets.

Oat hay consists of oats that are cut while still green, and while it does have a jointed structure, the focus is usually on whole seed heads rather than distinctly articulated stems and seed-like fruit as emphasized in the question. Alfalfa is a legume known for its leafy content, which promotes high protein levels crucial for certain equine diets, but it lacks the jointed stem characteristic and seed-like fruits mentioned. Barley straw, a by-product of barley grain production, primarily serves as bedding and does not have the same structural characteristics or nutritional benefits associated with the roughage in question.

Overall, Timothy hay stands out as the roughage that aligns with the description of having jointed stems and seed-like fruit.